The Ancient Order of Hibernians (AOH; Irish: Ord Ársa na nÉireannach) is an Irish Catholic fraternal organization. Members must be male, Catholic, and either born in Ireland or of Irish descent. Its largest membership is now in the United States, where it was founded in New York City in 1836, however, a reference to its existence as early as 1819 was found in a letter written from a Samuel Castwell to the eventual 7th President of the United States, Andrew Jackson. In the letter, Jackson had been nominated for membership into Castwell's Hibernian Society. The letter was dated May 26, 1819. The name was adopted by groups of Irish immigrants in the United States, its purpose to act as guards to protect Catholic churches from anti-Catholic forces in the mid-19th century, and to assist Irish Catholic immigrants, especially those who faced discrimination or harsh coal mining working conditions. Many members in the coal mining area of Pennsylvania had a background with the Molly Maguires. It became an important focus of Irish American political activity.